After seeing how expensive Nissan plastic air boxes are, how weak they are and how scarce they are second hand, I decided to make up a stainless steel air box like the Ozzies do.
With the help of Tinus, Michael and Peter Connan, we got the data required to manufacture.

12 engineering shops later and only 1 stepped up to the plate to tackle it.
After 3 rounds of negotiations I managed to cut the price down to the bare bone.
I won't say they are by any means cheap but are excellent quality and will last forever.
I was told if we can get volumes up the price will probably decrease per unit.

The air boxes are grade 304 stainless steel, so they will outlast the car !
They were designed around the Nissan original filter, but I'm sure they will take pirate filters as the lid is adjustable and seals down hard onto the filter without warping like the plastic box.

The outlet is a full 3" for maximum flow.

I'm thinking of having a 10/12mm diameter nipple added to the outlet pipe for the crank case/ oil catch can breather pipe to vent back into the engine.

Alex, it's exactly the same dimensionally as the ZD30/TD42 boxes, so it's a case of bolt out & bolt in.

If we can get a minimum of 5 units per batch the price will hopefully come down a bit.
Timing wise I can't give you a straight answer because my sample unit was a case of back and forth for alterations and quality approval before continuing, so no timing was accurately done on it.
I would hazard a guess of a week from order to completion, but that's a thumb suck at this point.
We'll know for sure after an order has been processed.

Just for reference, when I was designing this unit, I had a look (although just a look, not an actual try), and it looks like this unit will even fit in the GQ's. It even looks like there are already bolt holes for it...

So I am fairly convinced these can be made to work in any coil-spring patrol.